In a wireless cellular mobile network, a mobile station (MS) roams randomly. In a conversation process of a user, an MS moves and thus goes beyond the coverage of an originally accessed first base station (BS) and enters the coverage of a second BS, and in this case, it needs to connect the MS with the second BS through a handoff process for communication, so as to keep the conversation uninterrupted.
Currently, the wireless cellular mobile network provides two handoff technologies: hard handoff and soft handoff.
Hard handoff: when the MS moves and detects that signals of the first BS are deteriorated to a certain threshold or detects that signals of the second BS have higher intensity and quality, the MS reports to a mobile switching center (MSC). If the MSC determines that a hard handoff needs to be executed according to a certain algorithm, the MSC instructs the MS to perform the handoff to interrupt communication with the first BS and attempt to establish service connection with the second BS.
Soft handoff: in a code division multiple access (CDMA) wireless cellular mobile network, a CDMA MS is equipped with a RAKE multipath receiver similar to a rake, and supports the receiving operation via a plurality of signal paths simultaneously. When the MS moves and detects strong signals of the second BS, the MS may establish service connection with the second BS via a certain branch of the RAKE multipath receiver, without interrupting a service link with the first BS.
Both the above two handoff methods complete a handoff process between the first BS or the second BS and the MS by the cooperative work between the first BS and the second BS. When the difference of the network equipments concerned in the handoff is quite large, interoperability interfaces need to be designed on each of the associated network equipments and protocols need to be established for communication between the associated network equipments, so as to support the normal operation of the entire handoff process. If the wireless networks belong to different network systems, interoperability interfaces especially need to be designed between network equipments in the different network systems and protocols need to be established for communication between network equipments in the different network systems, so as to support the normal operation of the handoff process across networks. If a wireless network system is newly added in the future, interoperability interfaces need to be designed between network equipments in the current network system and network equipments in the newly added network system, protocols need to be established for communication between the network equipments in the current network system and the network equipments in the newly added network system, so as to support the normal operation of the handoff process between the current network system and the newly added network system. Currently, the design of such handoff is more complex, and has poor expansibility, high design difficulty, and high implementation costs.